Browse Definitions :
Definition

proxy server

Contributor(s): Matthew Haughn

A proxy server is a dedicated computer or a software system running on a computer that acts as an intermediary between an endpoint device, such as a computer, and another server from which a user or client is requesting a service. The proxy server may exist in the same machine as a firewall server or it may be on a separate server, which forwards requests through the firewall.

An advantage of a proxy server is that its cache can serve all users. If one or more Internet sites are frequently requested, these are likely to be in the proxy's cache, which will improve user response time. A proxy can also log its interactions, which can be helpful for troubleshooting

How proxy servers work

When a proxy server receives a request for an Internet resource (such as a Web page), it looks in its local cache of previously pages. If it finds the page, it returns it to the user without needing to forward the request to the Internet. If the page is not in the cache, the proxy server, acting as a client on behalf of the user, uses one of its own IP addresses to request the page from the server out on the Internet. When the page is returned, the proxy server relates it to the original request and forwards it on to the user.

Proxy servers are used for both legal and illegal purposes. In the enterprise, a proxy server is used to facilitate security, administrative control or caching services, among other purposes. In a personal computing context, proxy servers are used to enable user privacy and anonymous surfing. Proxy servers can also be used for the opposite purpose: To monitor traffic and undermine user privacy.

To the user, the proxy server is invisible; all Internet requests and returned responses appear to be directly with the addressed Internet server. (The proxy is not actually invisible; its IP address has to be specified as a configuration option to the browser or other protocol program.)

Watch an introductory video that explains proxy servers (definition continues below):

Users can access web proxies online or configure web browsers to constantly use a proxy server. Browser settings include automatically detected and manual options for HTTP, SSL, FTP, and SOCKS proxies. Proxy servers may serve many users or just one per server. These options are called shared and dedicated proxies, respectively. There are a number of reasons for proxies and thus a number of types of proxy servers, often in overlapping categories.

Forward and reverse proxy servers

Forward proxies send the requests of a client onward to a web server. Users access forward proxies by directly surfing to a web proxy address or by configuring their Internet settings. Forward proxies allow circumvention of firewalls and increase the privacy and security for a user but may sometimes be used to download illegal materials such as copyrighted materials or child pornography.

Reverse proxies transparently handle all requests for resources on destination servers without requiring any action on the part of the requester.

Reverse proxies are used:

  • To enable indirect access when a website disallows direct connections as a security measure.
  • To allow for load balancing between severs.
  • To stream internal content to Internet users.
  • To disable access to a site, for example when an ISP or government wishes to block a website.

Sites might be blocked for more or less legitimate reasons. Reverse proxies may be used to prevent access to immoral, illegal or copyrighted content. Sometimes these reasons are justifiable but sometimes justification is dubious. Reverse proxies sometimes prevent access news sites where users could view leaked information. They can also prevent users from accessing sites where they can disclose information about government or industry actions. Blocking access to such websites may violate free speech rights.

Watch a video introduction to reverse proxy servers (definition continues below):

Other types of proxy servers

Transparent proxies are typically found near the exit of a corporate network. These proxies centralize network traffic. On corporate networks, a proxy server is associated with -- or is part of -- a gateway server that separates the network from external networks (typically the Internet) and a firewall that protects the network from outside intrusion and allows data to be scanned for security purposes before delivery to a client on the network. These proxies help with monitoring and administering network traffic as the computers in a corporate network are usually safe devices that do not need anonymity for typically mundane tasks.

Anonymous proxies hide the IP address of the client using them allow to access materials that are blocked by firewalls or to circumvent IP address bans. They may be used for enhanced privacy and / or protection from attack.

Highly anonymous proxies hide even the fact that they are being used by clients and present a non-proxy public IP address. So not only do they hide the IP address of the client using them, they also allow access to sites that might block proxy servers. Examples of highly anonymous proxies include I2P and TOR.

Socks 4 and 5 proxies provide proxy service for UDP data and DNS look up operations in addition to Web traffic. Some proxy servers offer both Socks protocols.

DNS proxies forward domain name service (DNS) requests from LANs to Internet DNS servers while caching for enhanced speed.

Proxy hacking

In proxy hacking, an attacker attempts to steal hits from an authentic web page in a search engine's index and search results pages. The proxy hacker would have a either a fraudulent site emulating the original or whatever they felt like showing the clients requesting the page.

Here's how it works: The attacker creates a copy of the targeted web page on a proxy server and uses methods such as keyword stuffing and linking to the copied page from external sites to artificially raise its search engine ranking. The authentic page will rank lower and may be seen as duplicated content, in which case a search engine may remove it from its index.

This form of hacking can be also be used to deliver pages with malicious intent. Proxy hacking can direct users to fake banking site, for example, to steal account info which can then be sold or used to steal funds from the account. The attacker can also use the hack to direct users to a malware-infected site to compromise their machines for a variety of nefarious purposes.

Some means have been developed to compromise proxy abilities. Specially crafted Flash and Java apps, Javascript, Active X and some other browser plugins can be used to reveal a proxy user’s identity, so proxies should not be used on untrusted sites or anywhere that anonymity is important.

Website owners who suspect they have been the victim of a proxy hack can test the theory by searching for a phrase that would be almost uniquely identifying to the site. Their site should be prominent on the search engine results page (SERP). If a second site with the same content shows up, it may be a proxy page.

Eli the Computer Guy explains using proxies for hacking:

Proxy server security

Proxy servers in many forms enhance security but like many things in computing may be vulnerable themselves. To prevent DoS attacks and network intrusion, administrators should keep software up to date, use load balancing, enforce secure authorization and authentication and block unsolicited traffic, malicious and open proxies.

 

This was last updated in March 2019

Continue Reading About proxy server

Join the conversation

13 comments

Send me notifications when other members comment.

Please create a username to comment.

Proxy server is a great tool to crack blocked websites.
Cancel
My internet is blocked for all websites. How to unblock all sites? Please help me.
Cancel
use proxy servers to unloc some of the blocked websites


Cancel
Thank you. Now I have got an idea about proxy server.
Cancel
What type of proxy server do you use? Forward or reverse?
Cancel
Nice article! Thanks.
Cancel
Everything is clearly explained here. Thank you.
Cancel
Good explanation.
Cancel
What if these proxy sites are also blocked on your computer or internet server?
Cancel
Hi, this is complete and detail info with images and detail video. It makes easy to understand and read about proxy server. especially you are explaining about the functionality of the proxy server. Great work keeps it up and keeps sharing.
Regards,
Cancel
Wow, thanks you for your explanation. Nice Website.
Cancel
Nicely explained! What are your thoughts about investing into residential IP address instead of using Datacenter ones?
Cancel

Free or Paid Proxy Sites Hide A User’s Personal Information And Rest From Effort.

The web is completely done by the programming language it’s also named as HTML(Hyper Text Markup). You can see it in electronic gadgets like computers. This allows you to access all the websites with the help of internet service.

Its regards information passing from the websites, with a purpose. Its completely worldwide running application. Browsing is an application run in internet surf no one will run without complete identified by a distinct uniform resource locator.

Cancel

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

SearchSecurity

  • cybersecurity

    Cybersecurity is the protection of internet-connected systems, including hardware, software and data, from cyberattacks.

  • asymmetric cryptography (public key cryptography)

    Asymmetric cryptography, also called public key cryptography, uses a pair of numerical keys that are mathematically related to ...

  • digital signature

    A digital signature is a mathematical technique used to validate the authenticity and integrity of a message, software or digital...

SearchHealthIT

SearchDisasterRecovery

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • disaster recovery team

    A disaster recovery team is a group of individuals focused on planning, implementing, maintaining, auditing and testing an ...

  • cloud insurance

    Cloud insurance is any type of financial or data protection obtained by a cloud service provider. 

SearchStorage

  • hard disk drive (HDD)

    A computer hard disk drive (HDD) is a non-volatile memory hardware device that controls the positioning, reading and writing of ...

  • byte

    In most computer systems, a byte is a unit of data that is eight binary digits long. Bytes are often used to represent a ...

  • network-attached storage (NAS)

    Network-attached storage (NAS) is dedicated file storage that enables multiple users and heterogeneous client devices to retrieve...

Close